1. Field of the Invention
The invention relates to the field of oil well intervention. More particularly, the invention relates to a system of providing selective access to particular laterals for intervention wherein angle and orientation of the intervention string is ensured.
2. Prior Art
As one of skill in the art will undoubtedly appreciate one prior art method for intervening in a lateral was to simply measure the distance of pipe lowered into the hole. While this method has been used for many years, it has always been a difficult one because of the extreme distances involved. For example, where 100 feet of pipe is laid, a variance of two inches does not appear to be significant. This, however, is not the case when twenty thousand feet of pipe is contemplated. In keeping with the example, the two inches has become 400 feet. A distance off the mark of this magnitude can significantly hinder the working of the well. Therefore it is of interest to the industry to reduce variance to a minimum to maintain accuracy even at large depths.
It will be appreciated that spring loaded dogs are not new to the art and have been used for various purposes including positioning of tools however the combination of features that make the invention valuable have not before been contemplated.